A rapid, sensitive, and specific fluorescent test for picloram has been developed. Concentrated sulfuric acid 36N is added to the dry residue of picloram in glass test tubes, quartz tubes, or on a white porcelain plate. Yellow fluorescence is observed under long wavelength uv radiation when the test is performed in glass test tubes but with greater sensitivity under short wavelength uv radiation when done on a white porcelain plate or in quartz tubes.